// The MIT License (MIT)
//
// Copyright (c) 2015 Markus Herb
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
#ifndef KALMAN_SQUAREROOTBASE_HPP_
#define KALMAN_SQUAREROOTBASE_HPP_

#include "Types.hpp"

namespace Kalman {
/**
 * @brief Abstract base class for square-root filters and models
 * 
 * @param StateType The vector-type of the system state (usually some type derived from Kalman::Vector)
 */
template <class StateType>
class SquareRootBase {
 protected:
  //! Covariance Square Root
  CovarianceSquareRoot<StateType> S;

 public:
  /**
     * Get covariance (as square root)
     */
  const CovarianceSquareRoot<StateType>& getCovarianceSquareRoot() const {
    return S;
  }

  /**
     * Get covariance reconstructed from square root
     */
  Covariance<StateType> getCovariance() const {
    return S.reconstructedMatrix();
  }

  /**
     * Set Covariance
     */
  bool setCovariance(const Covariance<StateType>& covariance) {
    S.compute(covariance);
    return (S.info() == Eigen::Success);
  }

  /**
     * @brief Set Covariance using Square Root
     *
     * @param covSquareRoot Lower triangular Matrix representing the covariance
     *                      square root (i.e. P = LLˆT)
     */
  bool setCovarianceSquareRoot(const Covariance<StateType>& covSquareRoot) {
    S.setL(covSquareRoot);
    return true;
  }

 protected:
  SquareRootBase() {
    S.setIdentity();
  }
};

}  // namespace Kalman

#endif
